program Mnogougolnik;

{$APPTYPE CONSOLE}

uses
  SysUtils;

type
  ArrInt = array of integer;

var
  n, i, k: integer;
  mass: array of ArrInt;
  fin: textFile;
  flag: boolean;


begin
  assignFile (fin, 'input.txt');
  reset (fin);
  readln (fin, n);
  setlength (mass, n);
  for i:=0 to n-1 do
    setlength (mass[i], 2);
  for i:=0 to n-1 do
    read(fin, mass[i][0], mass[i][1]);
  flag:=true;
  k:=mass[n-1][0]*mass[0][1]-mass[0][0]*mass[n-1][1]+mass[0][0]*mass[1][1]-mass[1][0]*mass[0][1]+mass[1][0]*mass[n-1][1]-mass[n-1][0]*mass[1][1];
  for i:=0 to n-3 do
    if (k*(mass[i][0]*mass[i+1][1]-mass[i][1]*mass[i+1][0]+mass[i+1][0]*mass[i+2][1]-mass[i+2][0]*mass[i+1][1]+mass[i+2][0]*mass[0][1]-mass[0][0]*mass[i+2][1])<0) then
      flag:=false;
  if (k*(mass[n-2][0]*mass[n-1][1]-mass[n-1][0]*mass[n-2][1]+mass[n-1][0]*mass[0][1]-mass[0][0]*mass[n-1][1]+mass[0][0]*mass[n-2][1]-mass[n-2][0]*mass[0][1])<0) then
    flag:=false;
  if (k*(mass[n-1][0]*mass[0][1]-mass[0][0]*mass[n-1][1]+mass[0][0]*mass[1][1]-mass[1][0]*mass[0][1]+mass[1][0]*mass[n-1][1]-mass[n-1][0]*mass[1][1])<0) then
    flag:=false;
  if (flag) then
    writeln ('vipukluy')
  else
    writeln ('no');
    close (fin);
  for i:= 0 to n-1 do
  begin
    write (mass[i][0], '  ');
    writeln (mass [i][1]);
  end;
  readln;
end.
